Overview
EN ISO 8340:2005 - adopted by CEN as the European version of ISO 8340:2005 - specifies a laboratory method for determining the tensile properties of building sealants under maintained extension. The standard defines how to prepare, condition and test sealant specimens adhered between substrates and held at a fixed elongation so that loss of adhesion or cohesion can be observed and measured. It is intended for sealants used in joints in building construction.
Key topics and technical requirements
- Scope: Method for determination of tensile properties at maintained extension (not to be confused with extension-to-break tests covered in ISO 8339).
- Specimen preparation: Sealant is cast between two parallel substrates (mortar, anodized aluminium or glass) using 12 mm × 12 mm spacers and an anti-adherent backing film; manufacturer’s instructions (primers, mixing) are followed.
- Apparatus:
- Tensile test machine with extension rate (5.5 ± 0.7) mm/min.
- Refrigerated enclosure for −20 ± 2 °C conditioning.
- Ventilated oven at (70 ± 2) °C and distilled-water immersion containers for conditioning cycles.
- Separators to hold elongation at 25 %, 60 % or 100 % of original width (examples: to 15 mm, 19.2 mm, 24 mm).
- Measuring device readable to 0.5 mm for depth of failure.
- Conditioning: Two alternatives -
- Method A: 28 days at (23 ± 2) °C and (50 ± 5) % RH.
- Method B: Method A followed by three heat/water cycles (oven 70 °C / water immersion at 23 °C) and a 24 h return to lab conditions.
- Test temperatures: Specimens tested at (23 ± 2) °C and (−20 ± 2) °C; maintained elongation held for 24 h; any loss of adhesion/cohesion measured after testing.
- Reporting: Test laboratory, date, reference to EN ISO 8340, sealant name/type/colour, batch, substrate, primer, conditioning method, elongation %, depth of loss (mm) for each specimen and deviations from the standard.
Applications and users
- Who uses it: Sealant manufacturers (R&D and quality control), independent testing laboratories, product certifiers, specifiers, architects and façade engineers, and building-material procurement teams.
- Practical uses: Demonstrating sealant performance under sustained joint movement, comparing formulations, supporting technical data sheets, compliance testing for product standards and building specifications, and informing installation guidance for jointing products.
Related standards
- ISO 6927 - Sealants vocabulary (definitions referenced).
- ISO 8339 - Tensile properties (extension to break) - complementary method.
- ISO 13640 - Specification for test substrates used in jointing-product tests.
Keywords: EN ISO 8340:2005, sealant testing, tensile properties, maintained extension, building construction sealants, sealant conditioning, tensile test machine, jointing products.
